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Most studies and conceptualizations of tipping points in environmental and climatic systems have been conducted using natural science perspectives and approaches. Socio-scientific contributions—including Anthropology—are scarce. This has resulted in a limited understanding of the socio-cultural dimensions of tipping point phenomena at the local level. This paper contributes to ongoing discussion and provides an ethnographic study of local perceptions of desertification tipping points (DTPs) amongst Ovaherero pastoralists in Namibia's semi-arid Okakarara constituency. Following a qualitative approach, this study shows that experienced farmers are aware of these phenomena and have accumulated extensive knowledge enabling them to identify and anticipate DTPs in different, complementary ways. The paper discusses how DTPs are managed in a communally farmed setting and presents the challenges that livestock farmers face in practical prevention of DTPs. [ABSTRACT FROM AUTHOR]

Most studies and conceptualizations of tipping points in environmental and climatic systems have been conducted using natural science perspectives and approaches. Socio-scientific contributions—including Anthropology—are scarce. This has resulted in a limited understanding of the socio-cultural dimensions of tipping point phenomena at the local level. This paper contributes to ongoing discussion and provides an ethnographic study of local perceptions of desertification tipping points (DTPs) amongst Ovaherero pastoralists in Namibia's semi-arid Okakarara constituency. Following a qualitative approach, this study shows that experienced farmers are aware of these phenomena and have accumulated extensive knowledge enabling them to identify and anticipate DTPs in different, complementary ways. The paper discusses how DTPs are managed in a communally farmed setting and presents the challenges that livestock farmers face in practical prevention of DTPs. [ABSTRACT FROM AUTHOR]

This paper examines inter-ethnic relations between subaltern groups, in this case, Herero settlers on San land in the large arid Omaheke region in Namibia. Its stimulus is a remark made by a Herero Genocide activist who when asked about the genocide of "Bushmen" responded: "They must organize. They are just bushmen...." To make sense of this remark I examine the history of Herero/San relations by focusing on Herero colonization of San land and problematize San or Bushman servitude. I suggest environmental circumscription has increasingly limited Bushman exit options. On the level of meaning Herero ethnicity is enacted in everyday interactions ranging from razzias and villeinage, to rape and sexual exploitation and emphasize the lasting legacy of what Bourdieu terms "symbolic violence." Noting the similarities between Afrikaner and Herero colonization of the region, who both classified and treated Bushmen as a pseudo-species, I suggest that their pastoralism was privileged as part of an expansive settler colonialism precisely for its capacity to possess and dispossess, to eliminate and replace, and to exterminate the original inhabitants. [ABSTRACT FROM AUTHOR]

Kaokoland is a semi-arid to desert region in northwestern Namibia. The presence of numerous cascade tufa deposits in the area attests to a more humid, cooler climate during the past. A preliminary palaeontological survey of the tufas in 2017 resulted in the discovery of rich and diverse fossil faunas which indicate that the tufas accumulated during the late Pliocene and early Pleistocene. Some of the tufa deposits contain stone tools and burnt bones yielding evidence concerning ancient human activities. This paper provides a preliminary report on the Kaokoland Tufa Survey. [ABSTRACT FROM AUTHOR]

Fairy circles (FCs) are regular vegetation patterns found in drylands of Namibia and Western Australia. It is virtually unknown whether they are also present in other regions of the world and which environmental factors determine their distribution. We conducted a global systematic survey and found FC-like vegetation patterns in 263 sites from 15 countries and three continents, including the Sahel, Madagascar, and Middle-West Asia. FC-like vegetation patterns are found in environments characterized by a unique combination of soil (including low nutrient levels and high sand content) and climatic (arid regions with high temperatures and high precipitation seasonality) conditions. In addition to these factors, the presence of specific biological elements (termite nests) in certain regions also plays a role in the presence of these patterns. Furthermore, areas with FC-like vegetation patterns also showed more stable temporal productivity patterns than those of surrounding areas. Our study presents a global atlas of FCs and provides unique insights into the ecology and biogeography of these fascinating vegetation patterns. [ABSTRACT FROM AUTHOR]

The Chobe River, characterized by an unusual flood pulsing regime and shared between Botswana and Namibia, lies at the heart of the world's largest transfrontier conservation area (the Kavango-Zambezi Transfrontier Conservation Area). Significant ecological changes and vegetation conversions are occurring along its floodplains. Various scenarios for agricultural and urban water use are currently being proposed by the government of Botswana. However, the understanding of the river's annual flow regime and timing of the relative contributions of water from three different sources is relatively poor. In light of past and future climate change and variability, this means that allocating water between ecological flows and economic and domestic uses will become increasingly challenging. We reconstruct the inundation history in this basin to help ease this challenge. This paper presents a spatiotemporal approach to estimate the contribution of water from various sources and the magnitude of changes in the flooding extent in the basin between 1985 and 2010. We used time series analysis of bimonthly NOAA AVHRR and NASA MODIS data and climatologic and hydrologic records to determine the flooding timing and extent. The results indicate that between 12 and 62 % of the basin is flooded on an annual basis and that the spatial extent of the flooding varies throughout the year as a function of the timing of peak discharge in two larger basins. A 30-year trend analysis indicates a consistent decline in the average monthly flooded area in the basin. The results may prove useful in future water utilization feasibility studies, in determining measures for protecting ecological flows and levels, and in ecosystem dynamics studies in the context of current and future climate change and variability. [ABSTRACT FROM AUTHOR]

Indigenous natural food plants are critical to rural livelihoods, especially in arid and semi-arid regions where they contribute significantly to food security and social and economic welfare. The sustainability of these plants is therefore of paramount importance. This paper analyses the market conditions for marama bean (Tylosema esculentum) products, taking into account economic, social and cultural conditions. Information on local livelihoods was gathered through focus groups and in-depth interviews with key informants in Botswana, South Africa and Namibia. The market analysis for marama products was conducted using an STP (segment, target, position) framework, and willingness to pay for prototype products was evaluated using the contingent valuation method to analyse structured questionnaires directed at retail outlets. The study found that assuring the sustainability of local people's livelihoods while creating a larger market is only achievable through community organisations supported by a broad marketing strategy and using cultivated marama. [ABSTRACT FROM AUTHOR]

The principle of ecological restoration offers opportunities to re-vegetate disturbed areas cost-effectively after mining. The southern Namib is the northern tip of one the world's 25 biodiversity hotspots and is under pressure from mining and exploration activities. This paper provides a review of methods available for arid land restoration and assesses their applicability in the context of southern Namib restoration ecology. The techniques available are discussed under the headings: (a) provision of suitable landform and substrate and (b) facilitating natural processes. Landscaping man-made landforms to match their surroundings, the provision of rough surfaces and small water catchments as well as applying fresh topsoil are the main aspects to be considered. Growth-impeding soil properties such as toxicity, and acidic, saline and sodic conditions will require treatment to ensure natural plant re-establishment is feasible or replanting areas is successful. Seeding and relocating native plants are feasible options to accelerate natural plant succession that merit further development in the southern Namib. Apart from the involvement of mining and exploration companies, the use of these techniques will require good planning, a small team of dedicated staff, limited training and some very basic facilities to become a reality. [ABSTRACT FROM AUTHOR]

Semiarid regions are often affected by water scarcity and poor water quality. Seasonal changes in precipitation and drought events increase the pressure of use on water bodies and their pollution. In Central Northern Namibia, a high seasonal intra- and inter-annual variability of precipitation caused a 5-year lasting drought period. In the semiarid region, ephemeral channels and water pans represent the main water source, besides the institutionalized water supply. No systematic analysis of its quality has been conducted so far. The states of the surface waters at the end of the dry season in 2017 and the end of the rainy seasons in 2018 and 2019 were characterized by the analysis of physical–chemical parameters, focusing on usability. The first results show coarse contamination of the waters, which results in high turbidity values. Salt concentrations, such as Ca2+ and Na+, greatly increased due to evaporation. Al is present in high concentrations in solid and liquid phases, which indicates direct anthropogenic pollution. Spatial differences are evident in the study area and based on the precipitation gradient, land use, and population density. The waters cannot be used as drinking water without prior treatment. [ABSTRACT FROM AUTHOR]

The study evaluated patterns of land use and land cover (LULC) change in the Zambezi Region, Namibia between 1984 and 2010 using geospatial tools. Spatio-temporal dynamics of LULC changes were quantified using the post classification change detection method. The images were classified into five land use and land cover classes: forest land, shrub land, bare land, crop/grass land and other land. Landscape metrics were calculated using Fragstats to understand the landscape patterns and structural integrity of the landscape. The results showed that political transition (before and after independence) has resulted in dramatic decreases in patch density and increases in the interspersion and juxtaposition index values. The general pattern of LULC showed that the communal area compared to protected area became structurally diverse and ecologically more fragmented from 1984 to 2010. This study provides a foundation and baseline data demonstrating LULC alteration and landscape context suitable for monitoring future changes of protected and communal areas. Our approach is a novel way to assess the drivers and patterns of LULC under different land tenure types for natural resources conservation and sustainable land management in the dry lands of Southern Africa. [ABSTRACT FROM AUTHOR]

Abstract: This review is concerned with the aeolian geomorphology of the Namib Sand Sea, part of the Namib Desert in Namibia, south-west Africa, concentrating in particular on studies made over the past 50 years. The paper covers: sand sea organisation and dune patterns; and the dynamics of individual dunes. It demonstrates that studies in the Namib Sand Sea have been important to a much wider understanding of the geomorphological development of global sand seas. [Copyright &y& Elsevier]

Eight new refinements were implemented in the MODIS Land Surface Temperature and Emissivity (LST&E) product suite when transitioning from version 4 (V4) to version 5 (V5). The refinements were designed to improve the spatial coverage, stability, and accuracy of the product suite. Version 4.1 (V4.1) is an interim collection which uses V5 input products (MOD02, MOD03, MOD07, MOD10, and MOD35), but the LST&E retrieval algorithm is unchanged from V4 in which the split-window and day/night temperature retrieval algorithms are only partially incorporated, and not fully incorporated as in V5. A test dataset for the V4.1 product was produced by MODAPS for a 3-month period from July through September 2004, and after an initial evaluation period, it was decided to generate the V4.1 product from mission period 2007001 onwards as a continuation of previous years of V4 data. This paper compares MODIS retrieved surface emissivities between V4, V4.1 and V5 using the level-3 MODIS daily LST&E product, MOD11B1.Comparisons of MOD11B1 retrieved surface emissivity during the Jul–Sep 2004 test period with lab measurements of sand samples collected at the Namib desert, Namibia result in a combined mean absolute emissivity difference for bands 29 (8.55 µm), 31 (11 µm) and 32 (12 µm) of 1.06%, 0.65% and 1.93% for V4, V4.1 and V5 respectively. Maximum band 29 emissivity differences with the lab results were 4.10%, 2.96% and 8.64% for V4, V4.1 and V5 respectively. These results indicate that over arid and semi-arid areas, users should consider using MODIS V4 or V4.1 data instead of V5. Furthermore, users should be careful not to develop time series from a mixture of product versions that could introduce artifacts at version boundaries. [Copyright &y& Elsevier]

Abstract: Sustainable living in arid lands is the goal of many, including local residents, policy-makers and scientists. Research into desertification and climate change has the potential to significantly enhance livelihoods of resident people. It also has the potential to contribute to their capacity for risk reduction, improved natural resources management and adaptation to climatic and other changes in multi-stressor systems. This potential is not frequently realised. To effectively ensure that scientific insights and contemporary technologies are applied, active involvement of and feedback from those who apply and use the benefits offered by science and technology are required. Scientists and technologists have to address the diverse, mainly non-technical, aspects required to understand and cope with endemic climate variability, desertification and climate change. They need to appropriately tailor their approaches to disseminate results, and communicate their findings in a way that can be understood and readily implemented by policy-makers, politicians and communities. At the same time, they must learn from experiences gained through implementation by users at all levels. The challenges of making the necessary connections between the combinatory effects of desertification and climate change and their effective application are explored and tested. It was found that several key factors contribute to making the necessary connections to facilitate application on all levels of research advances. These include translation, information dissemination, communication, communication platforms, boundary organisations and leadership contributing to knowledge, motivation and capacity. The purpose of this paper is to assess research experiences from integrated land and water resource management, the application of renewable energy and energy efficiency, and local-level monitoring of natural resources and their application to the challenges of desertification and climate change. The conclusion of this assessment is the identification and description of a common framework that can be applied to address the challenges of desertification and climate change. [Copyright &y& Elsevier]

Abstract: Current and past settlement strategies in Central North Namibia are explored with historical aerial photographs, maps of indigenous land units (ILUs), GIS analysis, field observations and interviews on indigenous knowledge to improve understanding of livelihood strategies, described as an agro-sylvi-pastoral system. The objective is to assess the role of ILUs, indigenous fruit trees and termites in human settlement. Livelihood strategies take into account unpredictability of the semi-arid environment by having high diversity of ILUs on farm, not by selecting a certain elevation above water level as previously suggested. ILUs are classified according to hydrological properties and other aspects. Farming practices like kraal and homestead rotation and selection of ILUs with pronounced termite activity for cropping are suggested to maintain soil fertility. Selection of termite-rich areas causes a trade-off with homestead longevity and homesteads are located at least termite rich ILUs, but are encroached upon by termites. The amount and distribution of more fertile ILUs causes a trade-off between grazing and cropping when enclosed for farming. It is suggested that indigenous fruit tree species have been encouraged indirectly to grow on farm. It is shown that some fruit tree species never occurred in the area before. This is in contrast with the general view that fruit trees are left when farmers clear land. While some indigenous farming practices may degrade the land, this paper demonstrates that others don’t. [Copyright &y& Elsevier]

Woody plants are essential in ruminant nutrition in semi-arid regions particularly during the long dry season, however, their nutritional value varies considerably among species, seasons and geographical zones. A study was conducted to evaluate the seasonal variation in chemical composition and in-vitro gas production of woody plant leaves and their relationship. Leaves from sixteen (16) major plant species utilized by livestock were collected from six constituencies of Namibia in the wet season (January: summer), early-dry (May: winter) and late-dry (September: spring) season. There were significant influences of seasonal variations on dry matter (DM), ash, neutral detergent fibre (NDF) and soluble tannin (ST) concentrations of the plant species (p < 0.05). However, crude protein (CP) and acid detergent fibre (ADF) were not affected by season (p > 0.05). Rhigozum trichotomum (900 ± 13.9 g/kg), Vachellia hereroensis (902 ± 13.8 g/kg) and Baphia massaiensis (910 ± 13.2 g/kg) had lower DM content during the late-dry season as compared to wet and early-dry season. The NDF content was highest in Grewia bicolor (610 ± 48.1 g/kg DM) in the wet season and lowest in Vachellia mellifera (232.0 ± 41.5 g/kg DM) in the early-dry season. Seasonal variation influenced the rate of degradation but not the potential gas production, however, the species were not significantly influenced by seasonal variation for the parameters measured. Species with higher gas potential showed lower rates of degradation (r = − 0.71, p < 0.01). Though the chemical composition of the species was poorly correlated (p > 0.1) to the in-vitro gas production parameters, a positive correlation existed between ST and degradation rate (r = 0.52; p < 0.01). Seasonal variation influences the quality of woody plants and therefore, their leaves should be harvested during their optimal nutritious stage to improve livestock productivity. [ABSTRACT FROM AUTHOR]

Herbarium data have availed the much-needed long-term data that have constrained long-term and real-time phenological studies. Using herbarium specimens from the National Herbarium of Namibia, species, region, rainfall, latitude and longitude were regressed against the day of flowering to determine the effect of each variable on the day of flowering. This study used parameter estimates and the odds ratios from ordinal regression analysis to interpret the influence of the explanatory variables on the day of flowering. The results revealed that flowering dates of C. lugardiae have advanced by six days/decade during the period 1950 to 2010. Average summer rainfall decreased by approximately 3 mm per year from 1960 to 2015 in Namibia. Consequently, significant rainfall effects were recorded on the day of flowering for C. buphanoides, C. stuhlmannii subsp. delagoense and C. paludosum which have advanced by approximately 1 day/decade/mm, 1 day/decade/mm and 2 day/decade/mm during the period studied, respectively. Increase in latitude delayed day of flowering whilst an advancement of the day of flowering with an increase in longitude was observed. Substantial interaction effects among the explanatory variables were demonstrated. Combined effects of rainfall and latitude had a negative effect on the day of flowering whereas interaction effects of average summer rainfall and longitude had a positive combined effect on day of flowering. Our results, therefore, reveal the complex effects of rainfall and geographical location on flowering phenology of different Crinum species. The potential impacts of the phenological responses of different Crinum species on other organisms are discussed. [ABSTRACT FROM AUTHOR]

Effects of mine dump pollution on semiarid savanna vegetation were investigated in Kombat, Namibia. Vegetation structure, species richness, composition and diversity were compared between polluted and control sites. Concentrations of arsenic, chromium, copper, lead and zinc in soils were significantly higher closer to a 99-year-old mine dump than in a control site and exceeded internationally recommended guidelines by as high as 11 times. Mine dump pollution has significantly reduced woody plant densities, species richness and diversity in the affected area due to disappearance of pollution-sensitive species and preponderance of tolerant ones. Species composition and structure of vegetation close to the mine dump significantly changed, possibly due to negative impacts of heavy metals on recruitment as pollution-sensitive species died off, whereas tolerant species invaded the vacated ecological niches. Ordination analyses confirmed a strong pollution gradient, with measured heavy metals accounting for 57.3% of the observed variation in species data, suggesting that other factors are also important determinants in the area. It is recommended that the mine dump and its surrounds should be rehabilitated and regular monitoring should be carried out to remedy the situation and arrest further pollution of the surrounding environment. [ABSTRACT FROM PUBLISHER]

Savanna ecosystems are an important component of dryland regions and yet are exceedingly difficult to study using satellite imagery. Savannas are composed are varying amounts of trees, shrubs and grasses and typically traditional classification schemes or vegetation indices cannot differentiate across class type. This research utilizes object based classification (OBC) for a region in Namibia, using IKONOS imagery, to help differentiate tree canopies and therefore woodland savanna, from shrub or grasslands. The methodology involved the identification and isolation of tree canopies within the imagery and the creation of tree polygon layers had an overall accuracy of 84%. In addition, the results were scaled up to a corresponding Landsat image of the same region, and the OBC results compared to corresponding pixel values of NDVI. The results were not compelling, indicating once more the problems of these traditional image analysis techniques for savanna ecosystems. Overall, the use of the OBC holds great promise for this ecosystem and could be utilized more frequently in studies of vegetation structure. [ABSTRACT FROM AUTHOR]

Bush encroachment is a form of land degradation prominent worldwide, but particularly present in semi-arid areas. In this study, we mapped the spatial distribution of the two encroacher species, Acacia mellifera and Acacia reficiens, in Central Namibia, based on their different phenological behavior. We used constrained principal curves to extract a one dimensional gradient of phenological change from two hyperspectral images taken in different seasons. Field measurements of species composition and cover values were statistically related to bi-temporal differences in hyperspectral vegetation indices in a direct gradient analysis. The extracted gradient reflected the relationship between species composition and cover values, and the phenological pattern as captured by the image data. Cover values of four dominant plant species were mapped and species responses along the phenological gradient were interpreted. [ABSTRACT FROM AUTHOR]

In the context of climate change, the intensity, frequency, and duration of drought events have increased significantly, resulting in a profound impact on both natural ecosystems and socio-economic systems. In arid and semi-arid regions, precipitation is the main limiting factor for vegetation growth, and the ecosystems are very sensitive to climate change. Over the past 10 years, the Namibian government has declared national emergencies in 2013, 2016, and 2019 due to extreme drought events. The continued extreme drought has posed serious threat to the country's food security. Accurately monitoring the continuous drought events in Namibia and assessing their impact on the ecosystem is essential for drought risk management in the region. Based on long-term satellite observation of vegetation index and precipitation, we have evaluated the spatiotemporal dynamics of the three drought events, the vegetation–precipitation relationship across biomes, and the impact of continuous drought events on regional ecosystems. The results suggest that: (1) According to affected area and severity, the drought in 2019 was the most severe one, followed by the drought in 2013; the 2015–2016 drought spread over smaller spatial area, although it continued for two years; (2) Both the accumulated NDVI and precipitation in the growing season in Namibia increased from 2001 to 2010 while showing a significant decreasing trend during 2011–2020; (3) In Namibia, there is a significant correlation between the current season's accumulated precipitation and the current season's accumulated NDVI (r = 0.90, p < 0.01). The current season's accumulated precipitation is also well correlated with the next season's accumulated NDVI (r = 0.87, p < 0.01), and the correlation between the current season's accumulated precipitation and the next season's accumulated NDVI in a wet year is even stronger (r = 0.96, p < 0.01). This indicates that part of the precipitation in the current season may be stored in the soil for the next season's plant growth, which is more obvious in the northern plains with deep-rooted woody plants; (4) In 2013, the drought event suddenly changed from a long-term relatively humid state to an extremely dry state. During the ecological recovery stage, the NDVI during the growing season could not return to the state before the drought, causing irreversible damage to the Namibian ecosystem. In summary, the continuous extreme drought events during the last decade have caused profound impacts on the regional ecosystem. Much more attention should be paid to whether the extreme drought events will continue into the next decade and how the ecosystem can sustain a new equilibrium under a warmer and drier climate. [ABSTRACT FROM AUTHOR]

As part of SAFARI 2000, this study investigated fire severity associated with, and emissions released from, a wildfire that burned a total area of approximately 3200km2 of semi-arid savannahs in the region of Etosha National Park, Namibia. Percent tree cover derived from Moderate Resolution Imaging Spectroradiometer (MODIS) data was used to scale up from site-level field measurements to landscape-level emission fields. Empirical relationships relating fuel load and combustion completeness to tree cover were developed from field observations. These relationships were coupled to the remotely sensed data to determine the emissions released over the entire area burned. Emissions from this single fire event were estimated to be 1.4 x 1012g of CO2, 52.4 x 109 g of CO, 1.5 x 109g of CH4, 1.85 x 109 g of non-methane hydrocarbons (NMHC), and 2.4 x 109 g of particles less than 2.5 μm (PM2.5). A Normalized Burned Index difference (NBIdiff), representative of fire severity and modified for MODIS data was used to assess the heterogeneity of the burned areas, but no significant correlation was found between this NBIdiff and combustion completeness (CC). [ABSTRACT FROM AUTHOR]

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